Two-sided printing, such as two-sided direct thermal and/or two-sided thermal transfer printing, comprises the simultaneous or near simultaneous printing and/or imaging of a first (e.g., a front) side and a second, opposite (e.g., a back or rear), side of two-sided print media, such as two-sided direct thermal and/or two-sided thermal transfer print media. Two-sided direct thermal printing of media comprising a document such as a two-sided direct thermal receipt is described in U.S. Pat. Nos. 6,784,906 entitled “Direct Thermal Printer” and 6,759,366 entitled “Dual-Sided Imaging Element”, and U.S. patent application Ser. Nos. 11/159,461 entitled “Receipts Having Dual-Sided Thermal Printing”, 11/297,706 entitled “Dual-Sided Thermal Printing”, 11/675,649 entitled “Two-Sided Thermal Print Switch”, 11/757,529 entitled “Two-Sided Thermal Print Command”, and 11/757,553 entitled “Two-Sided Thermal Printer Control”, the contents of which are hereby incorporated by reference herein in their entirety for all purposes. Variations include combined direct thermal and inkjet printing as described in U.S. patent application No. 11/701,627 entitled “Direct Thermal and Inkjet Dual-Sided Printing”, the entire contents of which are also incorporated by reference herein for all purposes.
In two-sided direct thermal printing, a two-sided direct thermal printer is configured to allow concurrent printing on both sides of two-sided direct thermal media moving along a media feed path through the printer. In such printers a thermal print head is disposed on each of two opposite sides of the media for selectively applying heat to one or more thermally sensitive coatings on the respective sides thereof. The coatings change color when heat is applied, by which printing is provided on the respective media sides.
Two-sided thermal transfer printing of media comprising a document such as a voucher or coupon is described in U.S. patent application Ser. Nos. 11/779,732 entitled “Two-Sided Thermal Printer”, 11/780,959 entitled “Two-Sided Thermal Transfer Ribbon”, 11/834,411 entitled “Two-Sided Thermal Media”, and 11/835,013 entitled “Selective Direct Thermal and Thermal Transfer Printing”, the contents of which are hereby incorporated by reference herein in their entirety for all purposes. In two-sided thermal transfer printing, a two-sided thermal transfer printer is configured to allow concurrent printing on a first (e.g., a front) side and a second, opposite (e.g., a back or rear), side of two-sided thermal transfer media moving along a media feed path through the printer. In two-sided thermal transfer printers a thermal print head is disposed on each of a first and a second side of thermal transfer media for selectively applying heat to one or more thermal transfer ribbons interposed therebetween. One or more functional coatings (e.g., comprising a dye) from the thermal transfer ribbon(s) is transferred to the media when heat is applied, by which printing is provided on the respective media sides.